I'm ready to start building my business, and I'm stuck on how to promote and draw in new clients without spending $ on advertising. For those who are are doing at least 3-5 cakes a week (from home), what worked well for you?

With advertising you generally get what you pay for. Work out a budget for how much you can afford to spend on advertising, look at the different options available (print, radio, TV, online) and pick the media that will reach your target audience.

I would bring cakes to work for people to taste. I would decorate them to practice.
Once they see and taste your cakes word of mouth will get you orders.

Word of mouth was my best FREE advertising..Everytime a cake goes out I attach business cards inside the box etc..

Most wedding websites will let you have you a free listing. I signed up for every free listing I could. I also signed up for a Google Places account (also free) which is where about 40% of my clients find me.

I do pay for a listing on the knot. For me, the knot has worked out great. I book many weddings every year off of it.

I have also found good success from bridal shows. Not just any bridal show though. Find a show that has been around your area for several years that has a good reputation and draws a large crowd.

I dont know if facebook has the same appeal in your area, but where I live there is one name that most people have heard of more than the others and all she has is a page on facebook. The woman who has this 'business' (i'm not sure if she is actually a business officially or not) doesn't advertise anywhere else that I know of, but has hundreds of 'likes' to her page and is getting cake requests on her wall every day!